Here are a few suggestions, to get you started:​Before you go and buy something, check out your closet, there might be some forgotten​pieces that you can give a second life to.​ If there's nothing to work with there, then:Visit your local craft store for 100% recyclable polyester felt.Cork leather: The Little British Fabric ShopWool felt: FilzfeltMiscellaneous sustainable fabrics: Pure Fabricz​ & Offset WarehouseFor a wider list of online shops that sell sustainable materials you can check out Refinity